If the network administrator found that one of his routers is slow in performance better to check the traffic packet transactions. If any huge file size is been transferred better to disconnect the router and reconnect.
Possible to kill the network task packet so the network speed can be restored.
Explanation:
Moreover, possible to scan the end-user PC or workstation or desktop whether any malware or spyware is affected, if so better to remove that particular PC or workstation or desktop to disconnected from the router.
Updating the PC or workstation or desktop OS patches to be done at regular intervals.